package com.unittec.zk.provider.common;

import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Base64;

/**
 * @author wuxinwei
 */
public class RSAEncrypt {
    /**
     * 随机生成密钥对
     *
     * @throws NoSuchAlgorithmException
     */
    public static Map<Integer, String> genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(1024, new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey)keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey)keyPair.getPublic();
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 将公钥和私钥保存到Map
        Map<Integer, String> keyMap = new HashMap<Integer, String>();
        // 0表示公钥
        keyMap.put(0, publicKeyString);
        // 1表示私钥
        keyMap.put(1, privateKeyString);

        return keyMap;
    }

    /**
     * RSA公钥加密
     *
     * @param str
     *            加密字符串
     * @param publicKey
     *            公钥
     * @return 密文
     * @throws Exception
     *             加密过程中的异常信息
     */
    public static String encrypt(String str, String publicKey) throws Exception {
        // base64编码的公钥
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey =
            (RSAPublicKey)KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        // RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        return Base64.encodeBase64String(cipher.doFinal(str.getBytes(StandardCharsets.UTF_8)));
    }

    /**
     * RSA私钥解密
     *
     * @param str
     *            加密字符串
     * @param privateKey
     *            私钥
     * @return 铭文
     * @throws Exception
     *             解密过程中的异常信息
     */
    public static String decrypt(String str, String privateKey) throws Exception {
        // 64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes(StandardCharsets.UTF_8));
        // base64编码的私钥
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey =
            (RSAPrivateKey)KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        // RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        return new String(cipher.doFinal(inputByte));
    }

    public static RSAPublicKey getPublicKey(String str) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(str);
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(keyBytes);
        return (RSAPublicKey)KeyFactory.getInstance("RSA").generatePublic(x509EncodedKeySpec);
    }

    /**
     * 从文件获取RSA私钥
     *
     * @return RSA私钥
     * @throws InvalidKeySpecException
     */
    public static RSAPrivateKey getPrivateKey(String str) throws Exception {
        byte[] keyBytes = Base64.decodeBase64(str);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
        return (RSAPrivateKey)KeyFactory.getInstance("RSA").generatePrivate(pkcs8EncodedKeySpec);
    }

    // public static void main(String[] args) throws Exception {
    // // 生成公钥和私钥
    // Map<Integer, String> keyMap = genKeyPair();
    // // 加密字符串
    // String message = "wurlsk";
    // System.out.println("随机生成的公钥为:" + keyMap.get(0));
    // System.out.println("随机生成的私钥为:" + keyMap.get(1));
    // String messageEn = encrypt(message, keyMap.get(0));
    // System.out.println(message + "\t加密后的字符串为:" + messageEn);
    // String messageDe = decrypt(messageEn, keyMap.get(1));
    // System.out.println("还原后的字符串为:" + messageDe);
    //
    // }
}
